Back Up Power Supply

[Oddeiga]

I was wondering if a UPS rated at 275W would hinder my 480W power supply, and if so, anyone have recommendations for a backup power supply that will handle 480W + 2 monitors.

 

[Ice Czar]

very likely see the amp hour quote below, its unlikely to be able to deliver enough current in a timely manner, even considering you wouldnt need 480 watts

most UPS\SPS are rated in KVA (Kilovolt Ampere) not watts

and your very likely to actually only have a worse case draw of 200 to 300 watts
even with lots and lots of components at really high use
Id say the average consumption would be closer to 125 to 175 watts
(day to day average, not intensive CPU or GPU)

the supply converts AC current to DC current as its needed
Id use the APC UPS selector to get a rough estimate of the KVA range your looking for
(keep in mind the median values they employ may not accurately reflect what youve stuffed into your box)
and review
Power Conditioning 101
DIY UPS

the advantage of a UPS\SPS is not only suppress surges
and give you enough time to safely shutdown in the event of a blackout
but likely more importantly to even out the power to the supply in the event of a brownout, which is alot more common than a blackout
but batteries are fundementally different than VAC supplied by the utility
they are rated in AmpHours

Battery Power @ Howstuffworks
Normally, when you buy a pack of batteries, the package will tell you the voltage and current rating for the battery. For example, my digital camera uses four nickel-cadmium batteries that are rated at 1.25 volts and 500 milliamp-hours for each cell. The milliamp-hour rating means, theoretically, that the cell can produce 500 milliamps for one hour. You can slice and dice the milliamp-hour rating in lots of different ways. A 500 milliamp-hour battery could produce 5 milliamps for 100 hours, or 10 milliamps for 50 hours, or 25 milliamps for 20 hours, or (theoretically) 500 milliamps for 1 hour, or even 1,000 milliamps for 30 minutes.

However, batteries are not quite that linear. For one thing, all batteries have a maximum current they can produce -- a 500 milliamp-hour battery cannot produce 30,000 milliamps for 1 second, because there is no way for the battery's chemical reactions to happen that quickly. And at higher current levels, batteries can produce a lot of heat, which wastes some of their power. Also, many battery chemistries have longer or shorter than expected lives at very low current levels. But milliamp-hour ratings are somewhat linear over a normal range of use. Using the amp-hour rating, you can roughly estimate how long the battery will last under a given load.

If you arrange four of these 1.25-volt, 500 milliamp-hour batteries in a serial arrangement, you get 5 volts (1.25 x 4) at 500 milliamp-hours. If you arrange them in parallel, you get 1.25 volts at 2,000 (500 x 4) milliamp-hours.

unfortunately most SPS dont have the greatest surge protection (using MOV)
and true UPS arent all that common

my shortlist would be (from the best manufacturers down)
Liebert
APC
Tripp Lite
Belkin

for greater accuracy
use the Calculator in the How to buy a PSU thread to figure up your worse case senerio realworld draw
and then guess at an average or set a threshold you feel comfortable with
then factor in the efficiency of a given supply for the average load on it
(example 250W DC = 244W AC)
then factor in PFC (or not wont make much if any real difference)
and finally with a rough estimate of the Voltage AC draw in Watts Convert Watts to Kw and Kw to KVA
then shop for SPS in that KVA range

and advanced Power Conditioning Issues
MOV Sacrificial Components
Ground Currents

more on UPS and Batteries
http://computer.howstuffworks.com/question28.htm
http://science.howstuffworks.com/battery.htm